The Stovebolt Site Forums The Shop Area Engine Shop Clogged cooling system advice.

I’ve owned a ’49 Chevy 1 ton for about a year. Done lots to it and drive it once a week. Has a ’55 235. It warms up slow and keeps warming up until it peaks at 210. Takes about an hour during summer to get that hot.

Figured I’d change the thermostat and flush the system. Found out it doesn’t have a thermostat, probably because the engine is so clogged with gunk that it needs heavy coolant flow. Pulled block drain plug and it is so backed up with gunk that it won’t drain. Stuck in screwdriver to unclog it, didn’t drain.

What would be your advice? Does reverse flushing like the manual describe work? Are flushing guns available at auto parts stores? Any good chemicals for this procedure?

I'll bet I spent a couple hours with a long screwdriver, punch, chisel, hammer, and a shop-vac cleaning the water jacket on my 235. There was no way any flushing was going to remove all the rust and dirt in my block. All the junk had built up in the back of the block around and behind #6 cyl. I had to work through the freeze plug holes, and the coolant passages on the top of the block. (engine was out of truck) Then I'd tip the block over a few times, and suck it out with the vaccuum. I know radiator flush wouldn't have completely cleaned mine. Maybe yours isn't that bad.

Try and old trick for an old truck. Go buy a box of Arm and Hammer Washing Powder. Not baking soda, Washing powder. I dont know it they still have instructions on the box. Here is what I remember, drain the system of coolant, as best you can, remove the thermostat, reinstall the thermostat housing (no thermostat) install 2 cups of washing powder and 2 gallons of water leave off the radiator cap and crank the engine. Run it till it over heats. Or for about 15 min. Drain out the gunk and do it again and again untill you only have soapy water comming out the drain. Then one more time with just water no soap. Drain the system, install a new thermostat and antifreeze.
If the problem still persists you'll have to remove and dismantle the engine and vat that sucker in acid.
Good luck.

have the radiator core rodded. the tubes clog over time and w/ no mantainance... flushing once a year.
this involves the rad. removal and taken to a shop. they remove he top which exposes the core and slide a flat rod down each tube inside the radiator's core. the whole thing is re-soldered and you're almost good to go. be sure to flush the system once a year even though the common practice is every two.
and use the best e~glycol you can get.

CT I knew i forgot somthing. By all means have the radiator rodded before you acid vat the engine. You needed to have it rodded anyway if you did the engine thing.